Benzo(f)quinoline (BQ) has been recommended for study in the NTP as a mutagenic air pollutant and as a representative of nitrogen-containing aromatic heterocyclic compounds. It is present in various crude oils. Preliminary studies indicate that it may have carcinogenic potential. Before being tested in the bioassay program, disposition studies are needed to assess its absorption, distribution, metabolism and excretion. BQ was completely absorbed after oral exposure and was rapidly excreted as metabolites in approximately equal amounts into the urine and via the bile into the feces. No radioactivity persisted in the body after-acute exposure. Such studies will not only result in more appropriate dose settings for toxicity studies, but a better understanding of the mechanisms of toxicity of this compound.